1. Field of the Invention
This invention pertains to the field of natural pigments. More specifically, the present invention is concerned with the preparation of natural pigment complexes which have improved stability against oxygen, heat, light and moisture and improved water solubility as compared to the corresponding untreated pigments.
2. Description of Related Art
Pigments derived from vegetable or animal sources have long been used for various food and non-food coloring applications.
Such natural pigments as they are called, however, generally suffer from a disadvantage that they are readily susceptible to oxidation, heat, light and moisture degradation. Moreover, some of these natural pigments are either not water-soluble at all (carotenoids) or are not soluble in acidic solutions (bixin, norbixin).
An additional problem with the use of natural pigments, particularly in beverages, is that there is no natural pigment available having a yellow or orange color which is water-soluble at an acidic pH. In certain applications, it is satisfactory to emulsify a fat-soluble yellow pigment to obtain a yellow color. However, in some applications, such as beverages, the clarity that is required can only be met by a water-soluble pigment.
These disadvantages of natural pigments have greatly limited their overall applicability as coloring agents for various end uses. Accordingly, various expedients have been suggested to improve the stability of natural pigments. These have included the use of various additives to the pigments such as ascorbic acid or antioxidants. Alternatively, attempts have been made to control the environment surrounding these natural pigments such as the availability of oxygen, heat, light or moisture.
While these methods have met with some success in improving the stability of the pigments, none of these methods have improved the stability enough to enable the use of such natural pigments in a wide range of applications, particularly food products such as beverages. Moreover, these methods have not solved the problems associated with the water-insolubility of the pigments and particularly the insolubility of the pigments in an aqueous acidic medium.